Packaging is an important feature in protecting, selling and marketing most products. Packaging has broad applications, for example, in food products, medical devices, electronic components, industrial products, personal hygiene products, pet products, collectibles, jewelry, and the like. The specific features of such packaging will require properties for the particular application. For example, medical products and food products may often require a hermetic seal in order to prevent contamination of the product contained therein.
Food products, in particular, have rather stringent packaging requirements in order to preserve freshness and provide desired shelf life. Certain medical devices also demand strict packaging requirements in order to preserve sterility of such devices. In such applications, the package is typically vacuum-packed or gas-flushed and subsequently hermetically sealed. Although efficient packaging of products is mandatory, various aesthetic properties of a product package are also important. For example, the package appearance is highly important to consumer appeal. In addition, functional properties of the packaging such as reusability and ease of opening of a package are important considerations. In many of these applications, the ability to easily open a package will depend on the mechanical properties of the seal. Moreover, the ability of the sealant substrate to transfer heat at a high rate (heat/thermal conductivity) results in a significant reduction of seal dwell time, and enables higher cycle speed and lower energy consumption, of sealing processes with total material reduction (sustainability).
One such packaging structure utilizes a peelable seal. When a package having a peelable seal is opened, a sealing layer may be peeled away from a substrate. It is desirable for such peeling to be achievable with a low and relatively constant peel force. The elastic properties of the peelable seal ensure that failure of the seal does not occur from flexing and normal handling of the package. In some packaging prior art, peelable seals are constructed from multi-layered sheets. Examples of packaging systems having such seals include standup and regular pouches, bag-in-a-box, tray-type food packages, bottles or blister packages, overwrap and the like. Although some of these peelable sealing packages work reasonably well, it has been difficult to construct suitable packaging systems that will consistently form hermetic seals that resist leaking even when wrinkles, pleats, and gussets are present, and still be easily opened by an end user. Moreover, such earlier peelable packaging systems tend to operate over relatively narrow ranges, and, in particular, narrow temperature sealing ranges. Narrow sealing temperature ranges tend to result in packaging defects. For example, on the low end of the usable temperature range, leaking seals may be formed (not hermetically sealed). On the high end of the usable temperature range, non-peelable seals are formed which tear when opened.
Accordingly, there exists a need for improved peelable packaging systems that resist leaking by providing more caulking of the film seal channels, provide a hermetic seal, and open easily and seal consistently over a broad range of sealing temperatures without loss of desired peelable seal functionality as the seal ages.